Magnetic levitation systems, such as e.g. active magnetic bearings “AMB”, are commonly known in the art. Magnetic levitation systems are commonly utilized for supporting a rotating or oscillating object. Using magnetic levitation in rotating machinery results in for example: reduction of friction, oil-free operation, lower maintenance costs, and/or higher reliability when compared to traditional rotating machines with mechanical bearings. In many cases, an axial magnetic bearing comprises a disc on a rotating shaft and controllable electromagnets for directing axial forces to the disc. Magnetic bearings are often used in high speed applications where the rotational speed introduces high centrifugal forces into the rotating components. High centrifugal forces tend to expand radially the above-mentioned disc and this may lead to a situation where the disc becomes loose on the shaft. This may further lead into a situation where the disc moves radially due to rotational speed and mass unbalance of the disc and, as a corollary, adverse mass unbalance into the rotating system as a whole may result in.
In many cases, the above-mentioned disc is attached to the shaft with a shrink fit. This approach is, however, not free from challenges. One of the challenges is related to the fact that the shrink fit requires a large difference in connecting diameters in a way that the shaft has a greater diameter than the aperture of the disc when the shaft and the disc are at a same temperature and the disc is not installed on the shaft. This is because the disc must not get loose on the shaft when the disc, and thereby the aperture of the disc, is expanded by the centrifugal force. In practice, this means that the deformation at also the highest rotational speed has to be smaller than the difference between the above-mentioned connecting diameters of the shaft and the disc. The large difference in the connecting diameters requires more thermal expansion from the disc in order to be able to install the disc on the shaft. The attachment method based on the shrink fit is expensive from both manufacturing and assembling viewpoints. Additionally, handling hot objectives is a safety issue, and also the possibility to a failure in assembling the heated disc is always present.